The invention relates generally to a wheel bearing unit for motor vehicles and particularly to bearing units having at least two bearing parts which can rotate relative to one another and between which at least two roll body rows are arranged. The bearing parts each have an outer part, one part being fastened to the vehicle, the wheel and a brake disk being fastened to the other. Such bearing units are generally known, as for example from the publication "Kugellager-Zeitschrift", published in Germany in April 1972.
The known wheel bearing unit has an outer ring with several flange-like shaped parts, each of which have boreholes through which screw bolts are inserted. The screw bolts serve to fasten the outer ring to a connecting part provided on a vehicle. The known wheel bearing unit furthermore includes an inner ring with corresponding outer parts to which a wheel hub and a brake disk are fastened. This wheel bearing unit is completely proven in use. However, the form of construction of the outer ring requires a relatively compact connecting part with respect to the vehicle, since the screw bolts, required for attachment, must have a certain free extension length for the strength required. Furthermore, the screw bolts cannot be installed in the outer ring with a so-called impact screw inserter since the installation conditions in the area of the wheel hanging are usually relatively confined. This is particularly true for wheels which are connected with a drive. The manufacture of the outer ring is also relatively difficult, since very close tolerances are prescribed by the vehicle manufacturers for the threaded holes in the flange-like outer parts of the rings, especially with respect to the diameter, the inclination and the pitch diameter of the holes. In order to maintain these close tolerances, it is therefore necessary to manufacture the outer ring out of a case-hardened steel, since the threaded holes cannot be worked into the ring in its hardened state. One approach is to bore core holes into the ring in a prehardened state. During hardening, these core holes are then covered so that these regions remain soft for working in the thread. However, the danger that exists with the foregoing technique is that the core holes become distorted during hardening, and the close tolerances can thus be maintained only with difficulty.